Article comprising a planar optical waveguide mach-zehnder interferometer device, and method of making same

摘要

The interferometer device comprises two planar optical waveguides, each comprising core and cladding, each core having a centre, each planar optical waveguides comprising an interferometer arm extending between two coupling regions, with a refractive index Bragg grating in each interferometer arm, and with a maximum spacing between the respective core centres in the interferometer arms between the two coupling regions. The two interferometer arms are of essentially identical lengths. The planar optical waveguides are disposed on a major surface of a silicon body. The interferometer arms are parallel to each other over at least a substantial portion of the length of the interferometer arms. The Mach-Zehnder-type interferometer device is an add-drop filter. The maximum spacing is in the range 20-100 mu m and is selected to enable simultaneous formation of the refractive index Bragg gratings by simultaneous exposure of both cores to refractive index-changing radiation.